Field of the Invention
The present invention relates to a device for separating glycoglycerolipids and glycoglycerolipids and glycosphingolipids from a lipoid phase containing glycoglycerolipids and acylglycerides, or glycoglycerolipids and glycosphingolipids and acylglycerides, and is also directed to methods for separating glycoglycerolipids and glycoglycerolipids and glycosphingolipids from a lipoid phase.
Description of the Related Art
Glycolipids, glycoglycerolipids, glycosphingolipids and phospholipids are biogenic lipids that occur as membrane components in almost all biological systems and, as such they exhibit amphiphilic properties, i.e. a hydrophilic head group and a hydrophobic or lipoid tail group. The ubiquitous presence of glycolipids, glycoglycerolipids, glycosphingolipids, and phospholipids in virtually all living things also explains that lipid extracts (for example, vegetable oils or animal oils) thereof inevitably also contain glycolipids, and phospholipids.
Their amphiphilic properties give the glycoglycerolipids and glycosphingolipids a special importance in the solubilization of hydrophilic molecules in lipid phases such as oils.
Glycolipids, glycoglycerolipids, glycosphingolipids, and glycophospholipids are excellent biological emulsifiers with a high emulsion performance due to their amphiphilic properties. But this also explains why such lipids cannot be separated or only to a small extent with standard aqueous extraction methods. On the other hand, glycoglycerolipids and glycosphingolipids have an enormous economic potential due to their suitability as biological emulsifiers or biological surfactants. In practical applications, this relates in particular to the use as a cleaning agent for removal of oily or greasy residues. However, glycoglycerolipids and glycosphingolipids are also suitable for the emulsification of lipophilic active substances, e.g. for pharmaceutical formulations or pesticides, because they improve the absorption of these active substances by the target organism. In addition, evidence exists about immunomodulatory effects of various glycoglycerolipids and glycosphingolipids, which are also part of human cell membranes. Further, some glycoglycerolipids and glycosphingolipids are also attributed to have antibacterial and fungicidal properties. The emulsifying properties of the glycoglycerolipids and glycosphingolipids also cause superior interaction of lipophilic and hydrophilic components in baked goods.
On the other hand, glycoglycerolipids and glycosphingolipids have an enormous economic potential due to the fact that they are a bio-emulsifier. In practical application, this relates in particular to the use as a cleaning agent for removal of oily or greasy residues.
Consequently, the production of glycoglycerolipids and glycosphingolipids from biogenic lipid fractions or oils is of economic interest because they have a wide variety of uses in the food industry and especially in pastries and sweets.
Although it can be assumed that glycoglycerolipids and glycosphingolipids of various types are present in virtually all lipoid phases which can be obtained from biogenic materials, few studies for this exist in the scientific literature. In particular, the compositions of such lipoid phases, as well as the effects of these compounds on the solubilizing of other compounds also solubilized herein, are substantially unclear.
Glycoglycerolipids and glycosphingolipids have a strong affinity for lipid fractions despite their amphiphilic character due to their long fatty acid residues. Therefore, the distribution in aqueous extraction media from the prior art is only minor. However, liquid extractions were successfully accomplished with mixtures of organic solvents. By doing so, the use of alcohols is crucial in order to achieve a high separation efficiency. On a laboratory scale, the separation of glycoglycerolipids and glycosphingolipids is achieved by chromatography followed by solvent extraction of the adsorbed glycolipids. However, such adsorptive methods are not suitable on the industrial scale for economic and ecological reasons. U.S. Pat. No. 6,953,849 describes the extraction of glycolipids from rice bran oil by means of hot water steam. This cleaves the sugar residues, which means that parts of these compounds can be lightly separated by the steam extraction. In such a treatment of edible oils, a disadvantage is e.g. that at the steam temperatures applied herein and the duration of this steam exposure, an increased proportion of trans-fatty acids can occur in the edible oils, whereby such produced edible oils can become harmful. Furthermore, enzymatic methods for the removal of glycoglycerolipids and glycosphingolipids from lipid phases are known in the prior art. However, the glycoglycerolipids and glycosphingolipids are thereby modified in their structure, which severely restricts the later use of the separated glycolipid fraction or renders them unusable for further applications. Consequently, no process exists so far which permits a continuous and gentle recovery of larger amounts of biogenic glycoglycerolipids and glycosphingolipids.
In lipoid phases which must undergo a fining process in order to be freed from accompanying substances, separation of the glycoglycerolipids and glycosphingolipids per se is not necessary since in principle they do not lead to a relevant quality restriction (color, odor, transparency) of the refined product, if they are present in only small amounts. However, problems can arise by their strong binding capacity to water, alkaline earth metal ions and metal ions whose presence in a refined lipoid phase, for example in a vegetable oil is not desired. Also, depletion with conventional techniques of the above mentioned compounds is problematic from a lipoid phase that is heavily contaminated with glycoglycerolipids and glycosphingolipids.
According to the prior art, for the purpose of technical refining, lipoid phases are usually subjected to a so-called degumming process in order to convert hydratable compounds into a water phase or to effect aggregation via saponification of fatty acids, whereby the dissolved or aggregated compounds are obtained by processes of phase separation. By these methods, most of the hydratable and some nonhydratable phospholipids are separated off. Glycoglycerolipids and glycosphingolipids are partially degraded by hydrolysis and removed with the phospholipid fraction. In case of lipoid phases which have been purified by standard degumming methods, an intensive mixing procedure of the lipoid phase with a water phase can effect depending on the content of glycolipid compounds an emulsion that allows a subsequent phase separation by means of centrifugal force only partially or not at all. It could be shown that a further purification step under normal conditions (room temperature and normal pressure) either with an alkali solution or an acid (citric or phosphoric acid) is not sufficient also after an intensive mixing process for the removal of relevant amounts of glycoglycerolipids and glycosphingolipids, when subsequently a repeated separation by a separator is performed.
From the known properties of the glycoglycerolipids and glycosphingolipids, however, it can be assumed that water may bind to the OH groups of the sugar residues. Further, it can be assumed that glycoglycerolipids and glycosphingolipids adhere small amounts of water without formation of micelles. Alkaline earth metal and metal ions are bound by the same mechanism. It can be assumed that glycoglycerolipids and glycosphingolipids having multiple and complex sugar moieties are able to bind larger amounts of water and metal ions. Further it can be assumed that also glycoglycerolipids and glycosphingolipids tend to form micelles in lipoid phases. If water and metal ions are bound to sugar residues, the elimination of these substances by an aqueous medium is largely prevented by the fact that long nonpolar fatty acid residues strongly hinder the penetration of water into these structures and prevent a “rinsing out” of those compounds from the sugar residues to which they are electrostatically bound. This explains why, according to the prior art, it has hitherto been necessary to remove the fraction of the glycoglycerolipids and glycosphingolipids by means of chemical or enzymatic hydrolysis or distillative processes, whereby the content of water, as well as alkaline earth metal ions and metal ions still bound in a lipoid phase can be reduced to the required degree. Therefore, it is all the more surprising that the strongly hydrophilic salt compounds having a water shell in their inventive use form that causes hydrophilisation of glycoglycerolipids and glycosphingolipids, which allows their separation into an aqueous phase. Moreover, it was unexpected and surprising that the separated galactosydiglycerides have a high affinity for the starting lipid medium due to their hydrophilic-lipophilic balance. It is therefore highly probable that, by the introduction of the water-dissolved salts according to the invention and the water entry effected therewith, a combination of glycoglycerolipids and glycosphingolipids as micellar structures is made possible, whereby these can be separated by means of gravitational separation from a lipoid phase. This, however, does not fully explain the unexpectedly significant increase in the extraction efficiency of the process according to the invention when an intensive mixing of the aqueous media according to the invention is used.
Glycoglycerolipids and glycosphingolipids obtained from lipoid phases by extractive processes usually have very different structures and compositions. Often, they are associated with other structures via hydrophobic or hydrophilic interactions, for which they have served as “solubilizers” in the lipoid phase. This could explain why parts of the glycolipid fraction can be dissolved from structures to which they are electrostatically bound, or the glycoglycerolipids and glycosphingolipids are released together with the electrostatically bound structures only by organic solvents. This could also explain the large number of unknown compounds found in some glycolipid-rich extraction phases according to the invention, which have not been elucidated so far. One of these nonglycolipid compounds which are separated by the process according to the invention is e.g. phorbol ester.
From the above-mentioned aspects, it is all the more astonishing that it is possible to remove the glycolipid fractions contained in the lipoid phases by the intensive mixing procedure of the salt solutions according to the invention with a single aqueous extraction step or in lipoid phases having a very high content of glycoglycerolipids and glycosphingolipids, it is possible to remove these with fewer extraction steps than in the case with a low-energy input for the mixing process of the aqueous solutions into the lipoid phases. As a further unexpected and particularly advantageous effect of the removal of the glycolipid fraction is that thereby the binding capacity for water and electrolytes in the thus treated lipoid phase is reduced. Furthermore, there is virtually no foam formation in the case of subsequent separation of the lipoid phases with aqueous media. Surprisingly, it has also been found that aqueous solutions of guanidine or amidino compounds which are mixed with an intensive mixing procedure with a lipoid phase treated according to the invention, can be separated from the oil phase more readily by means of centrifugal separation, when this is done subsequent to the inventive separation of glycoglycerolipids and glycosphingolipids by an intensive mixing procedure of the salt solutions.
In the prior art, the separation of lipids from oils by means of a sodium chloride solution is disclosed, for example in WO 2012/109642 A1. Notwithstanding the undesirable corrosive properties of chloride salts such as sodium chloride which attacks and corrodes the processing devices, the inventors could demonstrate that only a specific selection of anions, as disclosed herein, can be used for the separation of glycoglycerolipids and glycosphingolipids according to the invention, and anions such as, for example chloride, bromide, iodide, nitrate, nitrite, sulfate, phosphate, and many others are not capable of solving the objective according to the invention.
EP 2 735 605 A1 describes the separation of rhamnolipids by extraction using an organic solvent. In this process, the rhamnolipids are transferred from an aqueous phase into an organic phase and are not separated from a lipoid phase. Moreover, no salts are used in the separation.
It is therefore the objective of the present invention to provide a device and a method for separating glycoglycerolipids or glycoglycerolipids and glycosphingolipids from a lipoid phase which comprises, inter alia, glycoglycerolipids and acylglycerides or glycoglycerolipids and glycosphingolipids and acylglycerides.
This objective is achieved according to the invention by the technical teaching of the independent claims. Further advantageous embodiments of the invention result from the dependent claims, the description, the figures, and the examples.